Association of torque requesting modules in a coordinated torque architecture

ABSTRACT

A powertrain control system for a vehicle includes a plurality of axle torque request modules that generate respective axle torque requests based on respective performance criteria of a vehicle, an axle torque arbitration module that generates a net axle torque request based on the plurality of axle torque requests, a plurality of propulsion torque request modules that generate respective propulsion torque requests based on respective performance criteria of an engine of the vehicle, a propulsion torque arbitration module that determines a net engine torque request based on the net axle torque request and the plurality of propulsion torque requests, and a propulsion torque control module that controls a plurality of actuators based on the net engine torque request such that the engine produces an output torque in accordance with the net engine torque request.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/959,697, filed on Jul. 16, 2007. The disclosure of the aboveapplication is incorporated herein by reference.

FIELD

The present disclosure relates to coordinating torque requests between aplurality of torque requesting modules and a plurality of actuators thataffect torque in a vehicle powertrain.

BACKGROUND

The background description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description that may nototherwise qualify as prior art at the time of filing, are neitherexpressly nor impliedly admitted as prior art against the presentdisclosure.

Powertrain control systems include a plurality of modules that require acertain amount of engine torque to operate properly. For example, anautomatic transmission control module may need to momentarily reducetorque from the engine in order to change transmission gears. Anotherexample may be an air conditioning clutch control module that needsengine torque to be increased a moment prior to engaging an airconditioning compressor clutch. The engine torque increase helpsmaintain a constant engine speed when the compressor clutch engages,particularly when the engine is idling.

In the prior art these various modules affect torque actuators directly.For example, the automatic transmission control module may retard aspark advance to the engine to reduce the engine torque during theshift. Similarly, the air conditioning clutch control module mayincrease the spark advance to increase the engine torque during themoment prior to engaging the compressor clutch.

As vehicle powertrain systems include more modules and more actuatorsthat affect torque, the architecture of the prior art becomes cumbersometo maintain and undesirably difficult to troubleshoot. As an example ofmore actuators, hybrid vehicles include an engine and an electric motorthat provide torque. Integrating the hybrid vehicle powertrain toexisting torque-modifying modules can be undesirably cumbersome with theexisting powertrain control architecture.

SUMMARY

A powertrain control system for a vehicle includes a plurality of axletorque request modules that generate respective axle torque requestsbased on respective performance criteria of a vehicle, an axle torquearbitration module that generates a net axle torque request based on theplurality of axle torque requests, a plurality of propulsion torquerequest modules that generate respective propulsion torque requestsbased on respective performance criteria of an engine of the vehicle, apropulsion torque arbitration module that determines a net engine torquerequest based on the net axle torque request and the plurality ofpropulsion torque requests, and a propulsion torque control module thatcontrols a plurality of actuators based on the net engine torque requestsuch that the engine produces an output torque in accordance with thenet engine torque request.

In other features an axle-to-propulsion torque conversion moduleconverts the net axle torque request to a propulsion torque requestbased on at least one of an axle gear ratio, a tire diameter, and atransmission gear ratio. The plurality of axle torque request modulesincludes a cruise control torque request module that generates one ofthe axle torque requests based on a cruise control set speed of thevehicle. An adaptive cruise control torque request module communicatesan axle torque correction to the cruise control request module based onan environment of the vehicle. The plurality of axle torque requestmodules includes a traction/drag control module that generates one ofthe axle torque requests based on slip between a tire of the vehicle anda road surface. The plurality of axle torque request modules includes avehicle over-speed protection module that generates one of the axletorque requests based on a predetermined speed limit of the vehicle. Theplurality of axle torque request modules includes a brake torquemanagement module that generates one of the axle torque requests basedon brake torque that is provided by brakes of the vehicle.

In other features the plurality of propulsion torque request modulesincludes a stall prevention module that generates one of the propulsiontorque requests based on a minimum torque that is needed to keep theengine running. The plurality of propulsion torque request modulesincludes an engine crank and stop module that generates one of thepropulsion torque requests based on whether the engine is newlyassembled. The plurality of propulsion torque request modules includesan engine capacity protection module that generates one of thepropulsion torque requests based on a predetermined catalyst temperaturelimit. The plurality of propulsion torque request modules includes atransmission torque request module that generates one of the propulsiontorque requests based on transmission gear shifts. The plurality ofpropulsion torque request modules includes an engine over-speedprotection module that generates one of the propulsion torque requestsbased on a predetermined maximum engine RPM. The plurality of propulsiontorque request modules includes an engine idle speed control thatgenerates one of the propulsion torque requests based on a desired idlespeed for the engine. The plurality of propulsion torque request modulesinclude reserve torque request modules that generate respective ones ofthe propulsion torque requests based on torque that will be needed fromthe engine to compensate for an impending load change on the engine. Thereserve torque request modules include an air conditioning compressortorque compensation module that generates a respective one of thepropulsion torque requests based on torque that will be needed from theengine to compensate for an impending load change due to an airconditioning compressor clutch engaging and disengaging. The reservetorque request modules include a catalyst light off module thatgenerates a respective one of the propulsion torque requests to changean exhaust gas temperature of the engine.

In other features the vehicle is a gasoline/electric hybrid vehicle andthe powertrain control system further comprises a hybrid control modulethat that determines how much torque of the net axle torque request isto be provided by an electric motor.

A method of operating a powertrain control system for a vehicle includesgenerating axle torque requests based on respective performance criteriaof a vehicle, generating a net axle torque request based on the axletorque requests, generating propulsion torque requests based onrespective performance criteria of an engine of the vehicle, determininga net engine torque request based on the net axle torque request and thepropulsion torque requests, and controlling a plurality of actuatorsbased on the net engine torque request such that an engine produces anoutput torque in accordance with the net engine torque request.

In other features the method includes converting the net axle torquerequest to a propulsion torque request based on at least one of an axlegear ratio, a tire diameter, and a transmission gear ratio. One of theaxle torque requests is based on a cruise control set speed of thevehicle. The method includes modifying the axle torque request based onan environment of the vehicle. One of the axle torque requests is basedon wheel slip between a tire of the vehicle and a road surface. One ofthe axle torque requests is based on a predetermined speed limit of thevehicle. One of the axle torque requests is based on brake torque thatis provided by brakes of the vehicle.

In other features one of the propulsion torque requests is based on aminimum torque that is needed to keep the engine running. One of thepropulsion torque requests is based on whether the engine is newlyassembled. One of the propulsion torque requests is based on apredetermined catalyst temperature limit. One of the propulsion torquerequests is based on transmission gear shifts. One of the propulsiontorque requests is based on a predetermined maximum engine RPM. One ofthe propulsion torque requests based on a desired idle speed for theengine. One of the propulsion torque requests is based on torque thatwill be needed from the engine to compensate for an impending loadchange on the engine. One of the propulsion torque requests is based ontorque that will be needed from the engine to compensate for animpending load change on the engine due to an air conditioningcompressor clutch engaging and disengaging. One of the propulsion torquerequests is based on increasing an exhaust gas temperature to warm acatalyst to a catalyst light off temperature.

In other features the method includes determining how much torque of thenet axle torque request is to be provided by an electric motor of ahybrid powertrain.

In still other features, the systems and methods described above areimplemented by a computer program executed by one or more processors.The computer program can reside on a computer readable medium such asbut not limited to memory, non-volatile data storage and/or othersuitable tangible storage mediums.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred embodiment of the disclosure, are intended forpurposes of illustration only and are not intended to limit the scope ofthe disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a functional block diagram of a vehicle powertrain; and

FIGS. 2A and 2B are a functional block diagram of a coordinated torquecontrol system for the vehicle powertrain.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is in no wayintended to limit the disclosure, its application, or uses. For purposesof clarity, the same reference numbers will be used in the drawings toidentify similar elements. As used herein, the phrase at least one of A,B, and C should be construed to mean a logical (A or B or C), using anon-exclusive logical or. It should be understood that steps within amethod may be executed in different order without altering theprinciples of the present disclosure.

As used herein, the term module refers to an Application SpecificIntegrated Circuit (ASIC), an electronic circuit, a processor (shared,dedicated, or group) and memory that execute one or more software orfirmware programs, a combinational logic circuit, and/or other suitablecomponents that provide the described functionality.

Referring now to FIG. 1, a functional block diagram is shown of avehicle powertrain 20. Powertrain 20 includes an internal combustionengine 22 that develops torque. The amount of torque is established byone or more actuators 24 that control at least one of fuel, ignition,residual exhaust gas or exhaust recirculation (EGR), number of cylindersfiring, and air flow, to engine 22 in accordance with commands from apowertrain control module (PCM) 26. It should be appreciated that engine22 may be a diesel engine, in which case ignition and air flow are notcontrolled by PCM 26; however, the fuel amount, injection timing,residual exhaust gas or EGR, and turbo boost could be controlled tocontrol the amount of torque. For example, EGR and boost control the airflow indirectly by displacing air with exhaust gas in a cylinder charge.A crankshaft position sensor 28 generates a signal that indicates aspeed of engine 22. Exhaust from engine 22 passes through a catalyst 30.Torque from engine 22 can be used for driving accessory loads. An airconditioning compressor 29 is an example of an accessory load. PCM 26can employ a compressor clutch 31 to selectively couple and decouple airconditioning compressor 29 from the engine torque. Other examples ofaccessory loads include an alternator, a power steering pump, an airpump, and the like.

Powertrain 20 may also include an electric motor 32 that provides torquein accordance with a torque command 34. The torque of electric motor 32can be combined with the torque of engine 22 to provide power forpowertrain 20. While electric motor 32 is shown coupled in series withthe torque output of engine 22, it should be appreciated that otherconfigurations are also contemplated to be within the scope of thisdescription. For example, electric motor 32 may be implemented as one ormore electric motors that provide torque directly to wheels 36 insteadof passing through a transmission 38.

The combined torque of engine 22 and electric motor 32 is applied to aninput of transmission 38. Transmission 38 may be an automatictransmission that switches gears in accordance with a gear changecommand 40 from PCM 26. An output shaft of transmission 38 is coupled toan input of a differential gear 42. Differential gear 42 drives axlesand wheels 36. Wheel speed sensors 44 generate signals that indicate arotation speed of their respective wheels 36.

PCM 26 receives an accelerator pedal position signal from a pedalposition sensor 46. PCM 26 also receives a set speed signal from acruise or speed control interface module 48. An adaptive cruise controlsensor 50 senses vehicles or other obstacles that are in a driving pathand generates a signal that indicates a distance to the obstacles. Thesignal can be used to adjust a set speed that is provided via speedcontrol interface module 48.

Referring now FIGS. 2A and 2B, a functional block diagram is shown of acoordinated torque control system 100. Coordinated torque control system100 can be implemented with PCM 26. FIGS. 2A and 2B join together todepict the complete functional block diagram. A first connector label“A” on FIG. 2A overlays a second connector label “A” on FIG. 2B. A firstconnector label “B” on FIG. 2A overlays a second connector label “B” onFIG. 2B. FIGS. 2A and 2B are collectively referred to as FIG. 2.

Coordinated torque control system 100 employs a torque request backbonemodule 102 that determines a propulsion torque demand and communicatesthe propulsion torque demand to a propulsion torque control module 104.Torque request backbone module 102 determines the propulsion torquedemand based on inputs from a plurality of torque requesting modulesthat are described below in more detail. The torque requesting modulesinclude modules that want to affect one or more of actuators 24 toaffect the engine torque. The propulsion torque demand represents thetorque needed from engine 22 in order to satisfy the needs of the torquerequesting modules such that they can carry out their respective controlstrategies.

Propulsion torque control module 104 controls one or more of actuators24-1, . . . , 24-M, i.e. actuators 24, based on the net propulsiontorque demand. Actuators 24 affect the engine torque. Examples ofactuators 24 include an ignition module that delivers an ignition sparkto the engine at a specified ignition timing, a fuel injection modulethat delivers a specified amount of fuel to the engine at a specifiedtime, an electronic throttle control module that moves a throttle valveto a specified opening, and the like.

Each torque requesting module is categorized as either an axle torquerequesting module or a propulsion torque requesting module. Axle torquerequesting modules control at least one of vehicle speed and vehicletraction with the road surface. Propulsion torque requesting modulescontrol the output torque of the engine and electric motor 32. The axletorque requesting modules are shown in FIG. 2A and will now be describedin more detail.

A pedal position signal 108 represents a vehicle acceleration requestedby the vehicle operator. Pedal position signal 108 may be generated bypedal position sensor 46. A driver torque request module 200 generates adriver torque request based on pedal position signal 108. The drivertorque request represents the axle torque needed to accelerate thevehicle in accordance with at least one of pedal position signal 108,engine speed signal 28, and vehicle speed signal 44.

A cruise control torque request module 202 generates a cruise controltorque request. The cruise control torque request represents an axletorque that is needed to maintain the vehicle at the set speed indicatedvia interface module 48. An adaptive cruise control torque requestmodule 204 may communicate with cruise control torque request module 202to modify the cruise control torque request based on the environmentsurrounding the vehicle. For example, adaptive cruise control torquerequest module 204 may request that the axle torque be reduced so thatthe vehicle decelerates and/or maintains at least a minimum followingdistance behind a second vehicle while the cruise control is active. Anactual following distance can be indicated by the signal from adaptivecruise control sensor 50.

Other axle torque requesting modules are represented by axle torquerequest modules 300-1, . . . , 300-J, referred to collectively as axletorque request modules 300. A first example of an axle torque requestmodule 300 is a traction/drag control module. The traction/drag controlmodule determines axle torque changes needed to control positive wheelslip and negative wheel slip. Positive wheel slip refers to slip betweena vehicle tire and the road surface due to excessive powertrain torqueduring acceleration. Negative wheel slip refers to slip between thevehicle tire and the road surface due to excessive braking axle torqueduring deceleration. The slip can be detected based on the signals fromwheel speed sensors 44.

A second example of an axle torque request module 300 is a vehicleover-speed protection module. The vehicle over-speed protection moduledetermines a maximum axle torque limit in order to keep the vehiclespeed below a predetermined speed limit.

A third example of an axle torque request module 300 is a brake torquemanagement module. The brake torque management module determines amaximum axle torque when the vehicle brakes are applied. The maximumaxle torque prevents the axle torque from overcoming the brake torque ofthe vehicle brakes.

A fourth example of an axle torque request module 300 is a stabilitycontrol module. The stability control module generates axle torquerequests based on a yaw rate of the vehicle. A stability control modulemay be included in an electronic stability control system, such as theStabiliTrak system sold by General Motors.

Torque control backbone module 102 includes an axle torque arbitrationmodule 302 that receives the various torque requests and/or limits fromdriver torque request module 200, cruise control torque request module202, axle torque request modules 300, and a torque cutoff control module306 (shown in FIG. 2B). Torque cutoff control module 306 is describedfurther below. Axle torque arbitration module 302 generates a net axletorque request based on the torque requests and/or limits andcommunicates the net axle torque request to an axle-to-propulsion torqueconversion module 304. Axle-to-propulsion torque conversion module 304converts the net axle torque request to a corresponding propulsiontorque request based on at least one of the gear ratios in the axledifferential gear 42, diameter of wheels 36, a gear ratio oftransmission 38, and torque converter gain. Axle torque arbitrationmodule 302 communicates the corresponding propulsion torque request to apropulsion torque arbitration module 308 that is included in torquecontrol backbone 102.

Discussion will now move to the various propulsion torque requestingmodules which are shown in FIG. 2B. A stall prevention module 402determines a minimum torque needed to keep engine 22 running. Stallprevention module 402 may increase the minimum torque based on inputfrom at least one of an engine crank and stop module 404 and an enginecapacity protection module 406. Engine crank and stop module 404increases the minimum torque request based on whether the engine is anew or green engine. A green requires a greater fuel injection pulsewidth to purge air from the fuel system when the vehicle is firstassembled. To compensate for the increased fuel injection pulse width,engine crank and stop module 404 may also communicate with propulsiontorque control module 104 so that it may retard the ignition timing andmaintain the engine torque constant despite the increased fuel injectorpulse width. Engine capacity protection module 406 provides a maximumtorque limit for engine 22 based on mechanical limitations of powertrain20. Examples of limitations include maximum torque limit of transmission38, a maximum temperature limit of catalyst 30, and the like.

Propulsion torque arbitration module 308 also receives propulsion torquerequests from one or more other propulsion torque request modules 500-1,. . . , 500-K, referred to collectively as propulsion torque requestmodules 500. An example of a propulsion torque request module 500includes a transmission torque request module that generates a torquerequest to reduce the engine torque during transmission shifts. Otherpropulsion torque request modules 500 can include at least one of anengine over-speed protection module and an engine idle speed controlmodule. The engine over-speed protection module determines a propulsiontorque limit to prevent the engine speed or RPM from exceeding apredetermined engine speed. The engine speed can be determined based onthe signal from crankshaft position sensor 28. The engine idle speedcontrol module determines the propulsion torque needed to maintainengine 22 at a predetermined idle speed during coasting or at idle withtransmission in 38 in drive or neutral.

Propulsion torque arbitration module 308 also receives reserve torquerequests from one or more reserve torque request modules 502-1, . . . ,502-N, referred to collectively as reserve torque request modules 502.Reserve torque refers to torque that will be needed from engine 22 inthe future. A first example of a reserve torque request module 502 is anair conditioning compressor torque compensation module. The airconditioning compressor torque compensation module requests a reservetorque so that the engine speed remains fairly constant when compressorclutch 31 engages and disengages.

A second example of a reserve torque request module 502 is a catalystlight-off module. When the engine is started cold the catalyst light-offmodule requests that the engine spark be retarded to increase theexhaust gas temperature and thereby heat catalyst 30 to its conversiontemperature. To compensate for the torque loss that is caused by theretarded spark the catalyst light-off module can also request that thethrottle opening be increased while the spark is retarded.

A third example of a reserve torque request module 502 is an intrusivediagnostic module. An intrusive diagnostic, such as an idle catalystmonitor, needs to change the air/fuel ratio of the engine to perform adiagnostic module. The intrusive diagnostic module therefore requestsreserve torque to compensate for the torque effect of a diagnosticprocedure that is about to execute.

In some situations the propulsion torque needs to be minimized bymomentarily turning off fuel and/or spark to the engine. Torque cutoffmodule 306 generates the torque requests for these situations, which caninclude at least one of a clutch fuel cutoff and a deceleration fuelcutoff. A clutch fuel cutoff occurs when the vehicle is equipped with amanual transmission and the vehicle operator disengages the clutch. Theclutch fuel cutoff prevents the engine speed from flaring beyond apredetermined speed when the clutch disengages and removes a load fromthe engine. The deceleration fuel cutoff occurs when the vehicle iscoasting above a predetermined speed. The deceleration fuel cutoff helpsincrease engine braking. Deceleration fuel cutoffs are also communicatedto axle torque arbitration module 302.

Propulsion torque arbitration module 308 generates a total requestedpropulsion torque based on the torque requests and/or limits from thevarious propulsion torque request modules and the axle torquearbitration module. Propulsion torque arbitration module 308communicates the total requested propulsion torque to propulsion torquecontrol module 104.

Torque control backbone 102 may also be configured to use with a hybridelectric vehicle. A hybrid electric vehicle includes engine 22 andelectric motor 32, which cooperate to propel the vehicle. In a hybridelectric vehicle, the total axle torque request from axle torquearbitration module 302 is communicated to a hybrid control module 700.Hybrid control module 700 determines how much propulsion torque will beprovided by electric motor 32 and how much will be provided by engine22. Hybrid control module 700 communicates the engine's share of thepropulsion torque to propulsion torque arbitration module 308. Theelectric motor's share of the propulsion torque is communicated toelectric motor 32 via torque command 34. Axle to propulsion torqueconversion module 304 may be combined with hybrid control module 700.Also, torque cutoff module 306 may communicate deceleration fuel cutofftorque requests to hybrid control module 700 instead of axle torquearbitration module 302.

Those skilled in the art can now appreciate from the foregoingdescription that the broad teachings of the disclosure can beimplemented in a variety of forms. Therefore, while this disclosureincludes particular examples, the true scope of the disclosure shouldnot be so limited since other modifications will become apparent to theskilled practitioner upon a study of the drawings, the specification,and the following claims.

1. A powertrain control system for a vehicle, comprising: a plurality ofaxle torque request modules that generate respective axle torquerequests based on respective performance criteria of a vehicle; an axletorque arbitration module that generates a net axle torque request basedon the plurality of axle torque requests; an axle-to-propulsion torqueconversion module that converts the net axle torque request into a firstpropulsion torque request based on an axle gear ratio, a tire diameter,a transmission gear ratio, and a torque converter gain; a plurality ofpropulsion torque request modules that generate respective propulsiontorque requests based on respective performance criteria of an engine ofthe vehicle; a propulsion torque arbitration module that determines anet engine torque request based on the first propulsion torque requestand the plurality of propulsion torque requests; and a propulsion torquecontrol module that controls a plurality of actuators based on the netengine torque request such that the engine produces an output torque inaccordance with the net engine torque request.
 2. The powertrain controlsystem of claim 1 wherein the plurality of axle torque request modulesincludes a cruise control torque request module that generates one ofthe axle torque requests based on a cruise control set speed of thevehicle.
 3. The powertrain control system of claim 2 further comprisingan adaptive cruise control torque request module that communicates anaxle torque correction to the cruise control request module based on anenvironment of the vehicle.
 4. The powertrain control system of claim 1wherein the plurality of axle torque request modules includes atraction/drag control module that generates one of the axle torquerequests based on slip between a tire of the vehicle and a road surface.5. The powertrain control system of claim 1 wherein the plurality ofaxle torque request modules includes a vehicle over-speed protectionmodule that generates one of the axle torque requests based on apredetermined speed limit of the vehicle.
 6. The powertrain controlsystem of claim 1 wherein the plurality of axle torque request modulesincludes at least one of a brake torque management module that generatesone of the axle torque requests based on brake torque that is providedby brakes of the vehicle and a stability control module that generatesone of the axle torque requests based on a yaw rate of the vehicle. 7.The powertrain control system of claim 1 wherein the plurality ofpropulsion torque request modules includes a stall prevention modulethat generates one of the propulsion torque requests based on a minimumtorque that is needed to keep the engine running.
 8. The powertraincontrol system of claim 1 wherein the plurality of propulsion torquerequest modules includes an engine crank and stop module that generatesone of the propulsion torque requests based on whether the engine isnewly assembled.
 9. The powertrain control system of claim 1 wherein theplurality of propulsion torque request modules includes an enginecapacity protection module that generates one of the propulsion torquerequests based on a predetermined catalyst temperature limit.
 10. Thepowertrain control system of claim 1 wherein the plurality of propulsiontorque request modules includes a transmission torque request modulethat generates one of the propulsion torque requests based ontransmission gear shifts.
 11. The powertrain control system of claim 1wherein the plurality of propulsion torque request modules includes aengine over-speed protection module that generates one of the propulsiontorque requests based on a predetermined maximum engine RPM.
 12. Thepowertrain control system of claim 1 wherein the plurality of propulsiontorque request modules includes an engine idle speed control thatgenerates one of the propulsion torque requests based on a desired idlespeed for the engine.
 13. The powertrain control system of claim 1wherein the plurality of propulsion torque request modules includereserve torque request modules that generate respective ones of thepropulsion torque requests based on torque that will be needed from theengine to compensate for an impending load change on the engine.
 14. Thepowertrain control system of claim 13 wherein the reserve torque requestmodules include an air conditioning compressor torque compensationmodule that generates a respective one of the propulsion torque requestsbased on torque that will be needed from the engine to compensate for animpending load change due to an air conditioning compressor clutchengaging and disengaging.
 15. The powertrain control system of claim 13wherein the reserve torque request modules include a catalyst light offmodule that generates a respective one of the propulsion torque requeststo change an exhaust gas temperature of the engine.
 16. The powertraincontrol system of claim 1 wherein the vehicle is a gasoline/electrichybrid vehicle and the powertrain control system further comprises ahybrid control module that that determines how much torque of the netaxle torque request is to be provided by an electric motor.
 17. A methodof operating a powertrain control system for a vehicle, comprising:generating a plurality of axle torque requests based on respectiveperformance criteria of a vehicle; generating a net axle torque requestbased on the axle torque requests; converting the net axle torquerequest into a first propulsion torque request based on an axle gearratio, a tire diameter, a transmission gear ratio, and a torqueconverter gain; generating a plurality of propulsion torque requestsbased on respective performance criteria of an engine of the vehicle;determining a net engine torque request based on the first propulsiontorque request and the propulsion torque requests; and controlling aplurality of actuators based on the net engine torque request such thatan engine produces an output torque in accordance with the net enginetorque request.
 18. The method of claim 17 wherein one of the propulsiontorque requests is based on a predetermined catalyst temperature limit.19. The method of claim 17 wherein one of the propulsion torque requestsis based on transmission gear shifts.
 20. The method of claim 17 whereinone of the propulsion torque requests is based on a predeterminedmaximum engine RPM.
 21. The method of claim 17 wherein at least one ofthe propulsion torque requests is based on torque that will be neededfrom the engine to compensate for an impending load change on theengine.
 22. The method of claim 17 further comprising determining howmuch torque of the net axle torque request is to be provided by anelectric motor.
 23. The method of claim 17 wherein one of the axletorque requests is generated based on a cruise control set speed of thevehicle.
 24. The method of claim 17 further comprising generating anaxle torque correction based on an environment of the vehicle, whereinthe one of the axle torque requests generated further based on the axletorque correction.
 25. The method of claim 21 wherein the at least oneof the propulsion torque requests is generated based on torque that willbe needed from the engine to compensate for an impending load change dueto an air conditioning compressor clutch engaging and disengaging. 26.The method of claim 21 wherein the at least one of the propulsion torquerequests is generated to change an exhaust gas temperature of theengine.